fibs and emg

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BLPhill

Distinguished member
Joined
Oct 10, 2008
Messages
211
Reason
PALS
Diagnosis
09/2008
Country
US
State
WA
City
Tacoma
Does anybody know what fibs are on a emg report?
 
Fibs (fibrilations) are spontaneous electrical activity of individual muscle fibers (muscle fibers are what make-up our muscles) when they become denervated. Positive sharp waves (PSW's) are thought to be the same thing. They are both a sign of active denervation.

They can both disappear if the muscle fibers have been reinnervated and there is no longer active denervation. If reinnervation has occured and active denervation has ceased, all that would be seen on the EMG is an increase in the size of motor unit action potentials (MUAP's). An increase in the size of MUAP's is a sign of reinnervation. Only if denervation is active while reinnervation is also occuring, will you see fibs / PSW's and an increase in the size of MUAP's at the same time on the EMG.

Just for the record: you can have the above scenario with ALS (i.e. if El Eschorial criteria are met) but you can also have it with many other conditions, too.
 
Thank you Wright, I have already been diagnosed with als but the emg report says negative for both fibs and psw. Just trying to understand what I'm looking at.
 
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